The invention is directed to an attachment pin for operatively holding a jaw portion of a translatable jaw of a chuck being used for the stretch forming of metals and more particularly to an attachment pin that has a twist lock connect/disconnect attachment to the jaw portion.
The state of the art disconnect pin of the type used to connect a jaw portion positioned within a stretch jaw chuck has the general configuration of a stud threaded on each end with a different thread pitch not unlike those used to secure an engine head to the block. The jaws of the type used for stretch forming are formed in several segments so as to conform to the end of the metal to be stretch formed. The jaw segments are placed within a conically configured chuck housing. The jaw portion is translatable forward and aft relative to the chuck housing for selected metal gripping pressure. The outer circumference of the chuck has spaced apart slotted apertures therethrough. For stretch forming, the metal workpiece to be formed is fastened securely at one end, positioned around a fixed in position male die configured to the approximate shape of the ultimate stretch formed metal workpiece and the free end of the metal workpiece is then placed between the jaw portions of the chuck. The jaws are then translated forwardly in the chuck housing to tighten the jaw portions onto the free end of the metal workpiece. The chuck and jaw portions are then translated together rearwardly stretching the workpiece to the shape of the die. The jaw portion is then translated relative to the chuck housing to release the jaw from the end of the now formed metal workpiece. The formed workpiece is then removed from the connected end and die. The same process is repeated for like formed parts.
When different configured metal parts are formed, the jaw portion must be changed to adapt to the configuration of different shaped metal parts to be held and stretched, i.e. two or more differently or like configured jaws may now be needed. To change the jaw portions the studs are unthreaded from the jaw portions and the jaws are removed. Different jaw portions are now installed in the chuck housing and the stud is inserted through the slotted apertures in the chuck housing and rethreaded into the new jaw portions. Because the jaw portions are generally constructed of Kirksite, they are brittle and after a period of use, the threaded apertures therein are destroyed rendering the jaw portions prematurely unusable. Also the exchange of jaw portions using the state of the art threaded studs takes considerable time due to the threading and unthreading of the studs from the jaw portions.
There has not been a satisfactory pin for the use described above to extend the life of the jaw portions and reduce the replacement time of jaw portions replacement until the emergence of the instant invention.